Electric power distribution lines are occasionally subjected to lightning strikes or grounding. Lightning strikes and groundings result in a sudden surge of electric current through the power lines. These sudden current surges may damage transformers, power lines and other related equipment in the electric power distribution grid. Since sudden surges of current, caused by lightning strikes or grounded power lines, usually last for only a fraction of a second, standard circuit breakers cannot be used to limit the current on the distribution lines because they shall keep the circuit open even though the fault condition has passed. Automatic circuit breakers, referred to as reclosers, are used in place of standard circuit breakers for protecting transmission lines against current surges.
Reclosers are designed to open a circuit when a current surge is sensed and then reclose the circuit within a few moments. When a recloser device is used to limit current flow through electric power lines, sudden current flows resulting from a lightning strike or a downed power line causes contacts within the recloser to separate, thereby opening the circuit and limiting the current flow. After opening the circuit, the recloser is designed to wait an interval of time, approximately one second in most cases, before bringing the internal contacts back together to close the circuit. If the current is still too high, the recloser opens the circuit again, thereby limiting the current through the lines. Again, the recloser closes the circuit after a few moments. Reclosers are designed to successively reclose only a few times, typically three times, before going into an open circuit configuration. In the open circuit configuration, the recloser remains open and can only be closed by physically turning a lever located on its surface.
In many cases, a fault condition may place several reclosers along an electric power line in their open circuit configuration This requires workers to travel to each of the reclosers to reset them back into their closed circuit configuration. The time and effort required to reset all of the reclosers along the distribution lines can add significantly to the cost and delay of restoring electrical power after a failure.